Android SIP - Failed to create Sip session

I am trying to call android using Android SIP API. I followed this tutorial and a few more similar tutorials. When I call the function

SipManager.makeAudioCall(String localProfileUri, String peerProfileUri, SipAudioCall.Listener listener, int timeout) 

      

        
        
        
      

    

I receive the Exception "Failed to create SipSession, is network available?" ... I found several ( here and here , but none of them solved the problem.